Improved SoG silicon substrates produced by internal gettering of metal impurities induced by millisecond-range flash lamp annealing

The research highlights for the further development of silicon based solar cell technologies focus on the cost reduction by applying inexpensive materials such as Solar Grade Multicrystalline Silicon (SoG mc-Si) and/or the simplification of the production process. Replacement of standard diffusion based doping by ion implantation reduces two of the solar cell production steps: elimination of the phosphosilicate glass (PSG) cleaning and edge isolation steps. Although ion implantation doping got very recently distinct consideration for doping of monocrystalline solar material, efficient doping of multicrystalline solar material remains the main challenge to reduce the costs. The usefulness of the plasma immersion ion implantation system (PIII) combined with advanced flash lamp annealing (FLA) was already validated. We have shown that within the millisecond annealing time, implanted phosphorous is electrically activated and silicon is recrystallized. Simultaneously, the diffusion of metal impurities and their activation is suppressed.